Cargo area lighting system for trucks

ABSTRACT

A lighting system using piped light is provided for the cargo space of a truck. A light source mounted on the truck body is energized by the truck electrical system through a switch in the cab. Plural lighting fixtures are mounted to the roof of the truck body for illuminating the cargo space. Each lighting fixture receives light which is piped through a separate light guide from the source to the fixture. There are two sets of lighting fixtures each of which is disposed in a linear array extending along a line from the front to the rear of the truck body. The light guides for one set of lighting fixtures are all disposed in a first enclosure and the light guides for the other set of lighting fixtures are all disposed within a second enclosure. Certain sections of the enclosures are provided with a transparent lens and certain light guides within the enclosures emit side light through the lens. A lighting fixture at the rear door of the truck body is provided with an optical switch for turning the lighting fixture on or off.

FIELD OF THE INVENTION

This invention relates to truck lighting systems; more particularly, itrelates to a lighting system for the cargo handling area of a truckusing piped light.

BACKGROUND OF THE INVENTION

As is well-known, trucks having fully enclosed cargo space within thetruck body are provided with a lighting system to facilitate loading andunloading of the cargo. Typically, the truck body, especially long haultrucks, is long relative to its height and width to provide the desiredcargo capacity. The longstanding practice in lighting the interior ofthe truck body has been to use a plurality of incandescent lamps mountedin the roof of the truck body and spaced from each other from front torear. Typically, the lighting fixtures comprise a lamp housing recessedinto the roof and enclosing an incandescent lamp and having a lightdistributing lens disposed on the housing between the housing and thecargo space so it is generally flush with the interior surface of theroof. This arrangement provides the required illumination without thelight fixture intruding into the cargo space.

The conventional incandescent lighting system described above has beenfound to be unsatisfactory because it is wasteful of energy, requiresongoing maintenance and it is sometimes used in such a manner that itconstitutes a fire hazard. In refrigerated trucks, i.e. those which havea refrigeration system for the cargo space, the heat generated by theincandescent lamps is largely dissipated into the refrigerated cargospace thus requiring more energy for refrigeration. Also, it is knownthat some truck drivers like to increase the illumination in the cargospace by replacing the standard low wattage incandescent lamps withhigher wattage with the result of increased heat generation andshortened life of the bulbs. This practice adds to the cost of bulbreplacement in the maintenance of the lighting system. Additionally, theconventional incandescent lighting system constitutes a fire hazard,especially when the truck body is loaded with cargo close to theincandescent lamp fixtures and the lights are inadvertently left on fora long time. Such conditions can cause truck fires which are not onlydangerous to life and limb but also constitute increased costs to thetrucking industry by reason of loss and increased insurance premiums.

There has been a longstanding need in the trucking industry for a safe,effective and energy efficient lighting system for the cargo space in acontainer body of a truck.

In the prior art, certain fiber optic or "light pipe" systems have beenproposed for use on vehicles. The Johnson et al. U. S. Pat. No.4,947,293 granted Aug. 7, 1990 discloses a clearance lighting system fora semi trailer cargo container body. The lighting system includes a corelight conducting material in the form of an elongated light conductingstrip provided with a cladding material to provide a light guide. Thecore and cladding are constructed to provide lateral light emission aswell as longitudinal propagation. A light source is adapted toend-illuminate the light guides for both sides of a container body froma single light source. A similar system which also provides a messagepanel is disclosed in Johnson U.S. Pat. No. 5,122,933 granted Jun. 16,1992.

The Moore et al. U.S. Pat. No. 4,740,870 granted Apr. 26, 1988 describesa fiber optic lighting system for boats. In this system, a plurality offiber optic cables extend from a central light source to respectiveplurality of remote light fixtures to provide lighting at differentlocations on the boat.

The Davenport et al. U.S. Pat. No. 4,811,172 granted Mar. 7, 1989describes an optical fiber lighting system particularly suited forautomobiles and air craft. The lighting system comprises subsystemssuitable for high and low beam illumination and rear illumination of anautomobile. Each subsystem comprises a high intensity light sourcecoupled to one end of each of a plurality of light pipes with eachhaving their other end positioned relative to a reflective element and alens. The reflective elements are arranged to provide a prescribedillumination pattern.

The Finch et al. U.S. Pat. No. 5,184,883 granted Feb. 9, 1993 disclosesan automobile lighting system similar to that described in theabove-referenced Davenport U.S. Pat. No. 4,811,172. The Finch et al.patent describes an indicating device that comprises a shutter having anopaque portion, a light blocking position in which the opaque portionblocks the passage of light from the output end of a light guide to alens and a non-blocking position in which light is allowed to passthrough the indicating device to the lens.

A general object of this invention is to provide an improved lightingsystem for the cargo space of a truck which overcomes certaindisadvantages of the prior art.

SUMMARY OF THE INVENTION

In accordance with this invention, an improved lighting system isprovided for the cargo space of a truck body. The lighting systemprovides desired levels of illumination throughout the cargo space byusing a piped light system which is highly efficient, simple andeconomical to install without intruding into the cargo space and whichrequires little maintenance. Further, the lighting system may becontrolled from the truck cab while the high voltage required for thelight source is confined to the light source housing which is disposedaway from the cab and on the outside of the truck body. By using lightpiped into the cargo space there is virtually no heat dissipation fromthe lighting system in the cargo space and therefore waste of energy inrefrigerated truck bodies is avoided, as compared with incandescentlamps. Further, the risk of fire hazard from the lighting system iseliminated.

Further, in accordance with the invention, the lighting system for theinterior of a truck body comprises an electrically energized lightsource mounted on the truck body, an electrical energizing circuitextending from the cab to the light source and a switch in the cab forturning the light source on or off. At least one set of lightingfixtures is provided in an array extending generally from the front tothe rear of the truck body and supported by the roof. Each one of a setof light guides extends from the light source to one of the lightfixtures and transmits light from the source to the respective fixture.

Further, in accordance with the invention, the set of light guides iscontained within an elongated light guide enclosure which is providedwith a transparent lens extending alongside the light guides. Selectedones of the light guides provide side light emission through the lensfor illumination of the adjacent area.

Further, in accordance with the invention, a lighting fixture isdisposed adjacent the rear door of the truck body and is provided withan optical switch for turning the fixture on or off.

A complete understanding of this invention may be obtained from thedetailed description that follows taken with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the truck body lighting system ofthis invention;

FIG. 2 is a cross-sectional view of lighting fixtures taken on lines2--2 of FIG. 1;

FIG. 3 is a perspective view of another lighting fixture; and

FIG. 4 is a cross-section view of an another embodiment of the lightingfixtures.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, there is shown an illustrative embodimentof the invention in a truck body interior lighting system using pipedlight. It will be appreciated as the description proceeds that theinvention may be used in other applications and may be realized indifferent embodiments.

FIG. 1 shows a trailer truck 10 having a cab 12 and a truck body 14, theoutline of which is shown in phantom lines. The truck body includes afloor 16, a roof 18, a front wall 22, side walls 24 and 24' and a rearwall including doors 26 and 26'. The truck body encloses a cargo spacewhich is refrigerated by a refrigeration unit 28.

The lighting system for the cargo space, in accordance with thisinvention, comprises a light source 32 suitably mounted on the exteriorof the front wall 22 above the refrigeration unit 28. The lightingsystem also comprises a plurality of lighting fixtures 34a, 34b, 34c,34d and 36 (referred to later herein as end-fire lighting fixtures)which are disposed within the cargo space, as will be described.Further, the lighting system comprises a plurality of light guides 38a,38b, 38c, 38d and 38e, each of which extends from the light source to aselected one of the light fixtures. Further, the lighting systemincludes a pair of light guide enclosures 42 and 44 which containselected sets of the light guides and which may provide strip lightingbetween the fixtures. The enclosure 42 includes enclosure sections 42dand 42e and also includes enclosure sections 42a, 42b and 42c which formpart lighting fixtures 43a, 43b and 43c (referred to later herein asside-fire lighting fixtures). The enclosure 44 includes enclosuresections 44a, 44b and 44c which form part of lighting fixtures 45a, 45band 45c (herein referred to as side-fire lighting fixtures). Theaforementioned components of the lighting system will now be describedin greater detail.

The light source 32 comprises a high intensity lamp of the typedescribed in the Robbins et al. U.S. Pat. No. 4,704,660 granted Nov. 3,1987. Such light sources are available from General Electric Company andLuminyte International Corporation. Light sources of this type arecommonly known as "light engines". The light source 32 is provided witha plurality of light ports each of which is adapted for optical couplingwith a light guide in a well-known manner. A light source is energizedfrom the truck electrical system through an electrical conductor 46which includes a manually actuable switch 48 mounted in the cab foroperation by the driver. The light source includes a voltage inverterfor developing a high voltage alternating current supply from the lowvoltage DC supply from the truck.

The light guides 38a, 38b, 38c, 38d and 38e are light conductors of thetype constructed of polymeric material with a suitable cladding. Thelight guides are preferably of the type known as solid core semi-rigidfiber optics such as that described in Zarian U.S. Pat. No. 4,957,347granted Sep. 18, 1990. Such light guides are available from the LuminyteInternational Corporation. The light guides are commonly referred toindividually as an "optic". The preferred light guide for this inventionis of a type identified as side-light fiber optic because it has theproperty of emitting light radially through the cladding around the coreand also conducts light axially for emission through the end of the core(referred to herein as a side-fire/end-fire light guide). It will beunderstood that the lighting system of this invention may also use lightguides extending between the light source and selected ones of the lightfixtures which do not provide side light emission but instead emit lightonly from the output end (referred to herein as end-fire light guides).

The light guides 38a and 38b extend from the light source 32 to theend-fire lighting fixtures 34a and 34b, respectively, through theside-fire lighting fixtures 45a, 45b and 45c. Each of the light guideshas an input end coupled with one of the ports of the light source andhas an output end in the respective lighting fixture, as will bedescribed. The light guides 38c and 38d extend from the source to theend-fire lighting fixtures 34c and 34d, respectively, through theside-fire lighting fixtures 43b and 43c. The light guide 38e extendsfrom the source to the end-fire lighting fixture 36 through lightingfixtures 43a, 43b, 34c, 43c, 34d and enclosure sections 42d and 42e.

All of the end-fire lighting fixtures 34a, 34b, 34c and 34d are of thesame construction and further, all of the light guide enclosure sections44a, 44b, 44c, 42a, 42b and 42c and all of the side-fire lightingfixtures 43a, 43b, 43c, 45a, 45b and 45c are of the same construction.Accordingly, description of only lighting fixture 34d and enclosuresection 42c will suffice and will be given with reference to FIG. 2. Thelight guide enclosure 42c comprises an elongated channel 52, suitably ametal extrusion, which opens downwardly. The channel 52 is of relativelyshallow depth and is adapted to be mounted to the roof or the upper wallof the truck body. It may be suitably inclined from the vertical by asmall angle. It is preferably recessed into the roof or wall but may besurface mounted if desired. The channel 52 is closed at the bottom by atransparent panel, suitably a clear plastic lens 54 which is supportedby in-turned flanges 55 on the edges of the channel. The light guides38c, 38d and 38e are disposed within the enclosure section 44c in aside-by-side relationship. The lens 54 is disposed between the lightguides and the cargo space of the truck body.

The side-fire lighting fixture 43c comprises the light guide enclosure42c and the side-fire light guides 38c and 38d which emit side-lightthrough the lens 54 to produce a strip lighting effect.

The end-fire lighting fixture 34d comprises a housing 56 which has thesame vertical cross-section as the channel 52. The housing 56 is closedat the bottom by a transparent light distributing lens 58 which issupported by the housing. A mirror 62 is mounted to the housing 56 andis inclined at an angle of about forty-five degrees relative to the roof18. The light guide 38d extends generally parallel with the roof 18 andhas its output end 64 disposed adjacent the surface of the mirror 62.Light emitted from the output end 64 impinges onto the mirror 62 and isreflected toward the light distributing lens 58 which disperses thelight over an area in the cargo space of the truck body. It is notedthat the light guide 38e extends through enclosure section 42c the lighthousing 56 into the adjoining enclosure section 42d to the lightingfixture 36. The arrangement of light guides 38d and 38e relative to thelight guide enclosure sections 42c and 42d and relative to end-firelighting fixture 34d is typical of the other lighting fixtures in thesystem. Light guide 38e extends through the light guide enclosuresections 42a, 42b and 42c, as well as lighting fixtures 34c and 34d andthen continues to light guide enclosure sections 42d and 42e to thelighting fixture 36.

The lighting fixture 36 is illustrated in FIG. 3. The light guide 38e ispreferably of the type which emits light only at the output end, i.e.without side light emission. Accordingly, the enclosure sections 42d and42e may take the form of an opaque rectangular conduit 52'.Alternatively, they may be of construction as the other enclosuresections except that the panel 54 may be opaque rather than transparent.The lighting fixture 36 comprises a housing 66 which has a transversecross-section the same as that of enclosure 42e. A light distributinglens 68 is disposed over the open side of the housing 66 fortransmitting light to the cargo space of the truck body. A mirror 72 ismounted to the housing 66 at an angle of about forty-five degreesrelative to the roof 18. The light guide 38e has its output end disposedadjacent the mirror 72. An optical switch in the form of a shutter 74 isprovided in the housing 66 for turning the lighting fixture on and off.The shutter comprises a manually actuable slide plate 76 which isslidably mounted in the housing 66 and provided with a handle 78. Theslide plate 76 is opaque and provided with an aperture 82 in alignmentwith the output end of the light guide 38e when the shutter is in the onposition and which is misaligned with the output end of the light guide38e when the shutter is in the off position.

Another embodiment of the end-fire and side-fire lighting fixtures willnow be described with reference to FIG. 4. In this embodiment, the lightguide enclosures 42 and 44 may be constructed without interruption forplacement of end-fire lighting fixtures and side-fire lighting fixturesat desired locations. Thus, the channel 52 and the lens 54 may beconstructed in one continuous piece of such length as is desired.

FIG. 4 illustrates end-fire lighting fixture 34d' (which correspondswith lighting fixture 34d of FIG. 2) and it also illustrates side-firelighting fixture 43c' (corresponding with fixture 43c) and it alsoillustrates enclosure section 42e' (corresponding to section 42e). Lightguide 38d terminates at fixture 34d' and is supported at its end by abracket 82. The bracket 82 has a flat body portion 84 which is securedby rivets to the top plate of channel 52. A pair of flanges 86 (only oneshown) extend laterally from the body 84 and are bent circumferentiallyaround the end of light guide 38d. The bracket 82 includes a mirrorsupport arm 88 integral with the body 84 and extending therefrom at anangle of about forty-five degrees. The arm 88 is provided with a flange92 on each of three sides which support the mirror 62 by being bent overthe edges thereof.

A light distributing lens 58' is mounted to the lens 54 in a position todistribute the light reflected by the mirror 62. The lens 58 is securedto the lens 54 by peripheral flange elements 94 which interlock with theperiphery of an opening in the lens 54.

It will be appreciated that this embodiment of the invention permitslocation of the end-fire lighting fixture 34d' with any arbitrary placealong the enclosure and that the side-fire lighting fixtures may belocated as desired.

In operation of the lighting system, the truck driver operates theelectrical switch 48 to turn on the lighting system to illuminate thecargo space in the truck body. When the switch 48 is turned on the lightsource 32 is energized and emits light from respective ports to theinput ends of the light guides 38a, 38b, 38c, 38d and 38e. Each of thelight guides conducts light to its output end and thence to therespective lighting fixtures 34a, 34b, 34c, 34d and 36. Each fixtureproduces a relatively intense light which is distributed over an area ofthe cargo space. Each of the light guides 38a and 38b also emits lightlaterally along its length through the lens 54 in enclosure sections 44aand 44b and light guide 38b extends through and emits side light throughthe lens 54 in enclosure section 44c. In a similar manner, light guides38c and 38d emit side light from enclosure section 42a and 42b whereasonly light guide 38d emits side light from enclosure section 42c. Also,when the light source 32 is turned on the light guide 38e conducts lightfrom its input end at the source to its output end at the lightingfixture 36. When the shutter 74 in lighting fixture 36 is turned off, nolight is emitted through the lens 68. When it is desired to haveadditional illumination in the vicinity of the doors 26 and 26', theshutter 74 is actuated to the on position and light is emitted throughthe lens 68.

Although the description of this invention has been given with referenceto a particular embodiment, it is not to be construed in a limitingsense. Many variations and modifications will now occur to those skilledin the art. For a definition of the invention reference is made to theappended claims.

What is claimed is:
 1. A lighting system for a truck of the type havinga cab for a vehicle driver and having a truck body for cargo, said bodyhaving cargo space enclosed by a floor, side walls, front and rear wallsand a roof, said lighting system comprising:an electrically energizedlight source mounted on the truck body, an electrical energizing circuitextending from the cab to the light source, a manually actuated switchelectrically connected in said circuit and mounted in the cab foroperation by the driver for turning the light source on or off, aplurality of lighting fixtures supported by the body in spaced relationwith each other, each fixture including an enclosure and a lightdistributing lens with the lens disposed between the interior of theenclosure and the cargo space, a plurality of light guides each havingan input end and an output end and being adapted to transmit lightreceived at the input end to and emitting said light from the outputend, the input end of each of said light guides being optically coupledto said light source for receiving light therefrom, each light guideextending from the light source to a selected one of the lightingfixtures with the output end thereof mounted to the enclosure of therespective fixture and optically coupled with the lens of the respectivefixture for emitting light thereon.
 2. A lighting system as defined inclaim 1 including:a selected plurality of said light guides extendingbetween said light source and one of said light fixtures, a light guideenclosure extending at least part way between said source and said onelight fixture, said enclosure including a light transmitting paneldisposed between the interior of the enclosure and the cargo space, saidselected plurality of light guides being disposed in said enclosure, andat least one of said selected plurality of light guides having acladding with an index of refraction which causes said cladding to emitlight laterally thereof through said panel.
 3. A lighting system asdefined in claim 1 wherein:said truck body includes a cargo door, anadditional lighting fixture supported on the container body adjacent thecargo door, said additional lighting fixture including a housing and alight distributing lens, an additional light guide having an input endand an output end and being adapted to transmit light received at theinput end to, and emitting said light from, the output end, the inputend of said additional light guide being optically coupled to the lightsource for receiving light therefrom, said additional light guideextending from the light source to the additional lighting fixture withthe output end thereof mounted to the housing of the additional fixtureand optically coupled with the lens of the additional fixture foremitting light thereon, and a manually actuated optical switchinterposed between the output end of the additional light guide and thelens for blocking or unblocking the transmission of light between theoutput end and the lens.